Saving plots from R to use with grid.exchange - r

Question

I would like to make a composite graphic which is 3 panels wide by 8 panels tall. Inside each of the panel would be a graphic that takes multiple R commands to create, like the 1st 3 graphics might be
#1
plot(c(2:20), c(2:20), ylab="", xlab="", axes=FALSE)
par(new=TRUE)
plot(c(1:18, c(1:18), xact="n"), type="l", xlab="", ylab="")
#2
plot(c(2:20), c(2:20), ylab="", xlab="", axes=FALSE)
par(new=TRUE)
plot(c(1:18, c(1:18), xact="n"), type="l", xlab="", ylab="", col=2)
#3
plot(c(2:20), c(2:20), ylab="", xlab="", axes=FALSE, col=3)
par(new=TRUE)
plot(c(1:18, c(1:18), xact="n"), type="l", xlab="", ylab="")
and then I want to use a command like this to display those 3 side by side:
grid.arrange(plot1, plot2, plot3)
I don't understand how to save #1, #2, and #3 each to be plot1, plot2 and plot3. Examples of how to save plots all seem to be based on a single plot command, not multiple commands to make the plot. The help page says grob but doesn't explain what an acceptable grob might be, or how to make it. Should I screenshot each of those and save it as a jpeg file?
thanks for any help.

Answer 1

You can set par(mfrow = c(8, 3)). This will draw each plot in a single panel of an 8 x 3 grid. And will only move on to draw the next plot when plot.new is (implicitly) called.
par(mfrow = c(8, 3))
par(mar = c(0.5, 0.5, 0.5, 0.5)) # Otherwise margins are too large for 24 plots
for(i in 1:24) {
plot(c(2:20), c(2:20), ylab = "", xlab = "", axes = FALSE, col = 3)
par(new = TRUE)
plot(c(1:18), c(1:18), xaxt = "n", type = "l", xlab = "", ylab = "")
}

Answer 2

Update & solution:
Don't use grid.arrange(), don't use jpeg(), recordplot(), pdf() or ggplot...
The below code worked by adding features to the original plots. Then it helps (within RStudio) exporting results as high resolution PNG. I can label the row/columns separately well enough in MS Word.
par(mfrow=c(1,3))
#1
plot1=plot(c(2:20), c(2:20), ylab="", xlab="", axes=FALSE)
par(new=TRUE)
plot1= plot1 + plot(c(1:18, c(1:18), xact="n"), type="l", xlab="", ylab="")
#2
plot2 = plot(c(2:20), c(2:20), ylab="", xlab="", axes=FALSE)
par(new=TRUE)
plot2 = plot2 + plot(c(1:18, c(1:18), xact="n"), type="l", xlab="", ylab="", col=2)
#3
plot3 = plot(c(2:20), c(2:20), ylab="", xlab="", axes=FALSE, col=3)
par(new=TRUE)
plot3 = plot3 + plot(c(1:18, c(1:18), xact="n"), type="l", xlab="", ylab="")